Whether you like taking your Acura down the PCH and on challenging roads like the Tioga pass, have to drive down the I-5 to L.A. now and then, or you just use it as your commuter, a good set of brakes can make a big difference both to your driving enjoyment and your safety. Here's what you should look for when trying to diagnose brake problems.
The Parts of Your Acura's Braking System
A lot goes on when you push the brake pedal in your car. The braking system can be broken down into subsystems, each with its own function.
First, fluid pressure needs to be applied to operate the brakes:
Brake pedal - This foot operated lever pushes a shaft.
Master Cylinder - The shaft pushes brake fluid from a reservoir through the braking system.
Brake booster - This device helps push the shaft inside the master cylinder. Most boosters use a large bladder that expands using engine vacuum pressure, while hybrids use an electric booster.
Brake lines - These metal lines transfer fluid from the master cylinder to the brakes.
Brake hoses - These hoses link the brake lines with the braking components on the wheel hub. This contains the brake fluid while bending and flexing as the wheels steer and the suspension goes up and down.
All Acuras from the first Legend to the new RSX use disc brakes on every wheel:
Rotor - This is a large metal disc mounted to the hub. It spins with the wheel.
Caliper - This hydraulically-operated C-clamp has one or more pistons that are pushed by the brake fluid running through the system. It's fitted to a bracket mounted to the hub, keeping it stationary.
Pads - The caliper pushes the pads into the rotor. The friction between the pads and the rotor slow down the vehicle.
Hardware - There are several small parts that help the pads and caliper move back and forth including metal plates that go over the caliper bracket and rubber boots that protect the caliper mounting bolts.
The parking brake is a separate mechanical system:
Parking brake cable - This is pulled by the parking brake lever. This pushes the shoes into the drums molded into the inside the rear brake rotors.
Parking brake servo - On Acuras with an electric parking brake, an electric motor clamps the caliper, pushing the brake pads into the rotor on the rear brakes.
Most Acuras use “drum in hat” parking brakes which have a set of mechanical drum brakes beneath the rear brake rotors:
Shoes – These semi-circular parts push outward when the brake lever is pulled. They have a layer of material that's similar to what is used on brake pads.
Drum – This bowl shaped metal piece rides on the hub. Just like the rotor and pads on a disc brake, contact between the drum and shoes provides braking force. A drum in hat rotor has a drum built into the central part that slides over the hub.
Hardware – Drum brakes use springs to keep the shoes away from the drum when not in use, spring mounts that keep the shoes attached while allowing them to move, and an adjuster to move the shoes outward as the pad material wears down.
Anti-lock braking system-equipped cars add a few more components to the brake system:
ABS sensor – Detects wheel speed
Reluctor wheel – This gear-shaped ring passes by the ABS sensor as the wheel spins. The sensor counts the number of times the raised areas of the reluctor wheel pass by to calculate speed. This part is usually built into the hub.
Valve – Releases fluid pressure from the brake system to prevent the brakes from locking up.
What Can Go Wrong With My Brakes?
As the brakes are used, material rubs off of the pads, shoes and rotors. Brake pads have small metal tabs called “indicators” that rub against the rotors once the pad material is close to its minimum thickness, causing a prolonged squeaking noise to signal the need for replacements. If the material wears off completely, the metal backing plate can contact the rotor, scarring the surface. Rotor and drum thickness can be measured by a technician using a brake micrometer, while shoes need to be visually inspected. Although it's technically possible for the drum area inside the hat of the rear rotor to get too thin from use, the rotors should need replacement from regular brake wear long before the parking brake can remove that much metal.
Brake hoses can crack with age, and the rubber can flake off. If the rubber inside the hose starts to flake, it can move toward the hose surface when brake fluid moves in one direction, then outward to block the hose when the fluid moves in the other direction, effectively creating a one way valve. This can prevent the caliper from operating so it can't brake, or prevent the caliper from releasing, locking up the brake.
Brake lines can be kinked by accidents, preventing fluid flow. They can also rust out due to salt exposure or from moisture that has collected in the brake fluid.
The seals on the master cylinder can dry up, allowing fluid to leak out. This often results in brake fluid leaking out of the rear of the cylinder onto the brake booster, peeling off the paint. Likewise, the brake booster's bladder can crumble, preventing it from creating a seal in the vacuum chamber. Whether you have a failure of a vacuum or electric brake booster, the unassisted brakes will be much harder to operate.
ABS valve body failures are rare, but when they do happen, diagnosis can be tricky. This is one job best left to a professional. However, damaged sensors and reluctor wheels are much easier to replace.
Where Can I Get Quality Brake Components for My Acura?
AcuraPartsClub.com carries everything you need to keep your Acura running like new from brake rotors to bumper covers. Everything we sell is OEM, so you know you'll always get a quality factory part. Our site lets you find parts by part numbers, VINs, vehicle models and even keywords like “hose” and “sensor.” Have questions about a part or application? Our factory-trained parts personnel can answer them.